Here are the specs:
Input: 27.5 VDC at 37A
Output 115VAC 400Hz at 4.5A
This device basically has an electric motor that spins powered by the 28VDC generating a 400Hz wave corrected in the inverter circuitry to be stable at 115VAC tension.
This device is very very noisy but to do some tests looks like to be pretty good :)
Once it came I had to open it as the voltage output was steady at 85V...there is a potentiometer you can regulate to change output frequency: when I removed the cover the pot had an unsoldered connection, so I restored it and now perfectly works.
Also had to adjust the motor speed screw at the end of motor shaft to achieve a more correct frequency output.
Here are few shots and a video of spin up :)